how to unlock a PDF file

[greenburn]

Hi all!
As you may already yourself fully be aware of, PDF files sometimes come with annoying security locks that don't let you copy the text. As a student that does a lot of research this feature must be the worst idea ever. I know there are scripts/programs online that will unlock the PDF file for you, but I want to learn to unlock PDFs myself.
Can anybody provide some insight as to what exactly needs to be changed in the PDF file to remove the security locks? Is a disassembler necessary? Once again, I am not looking for links to scripts/programs online that will do it for me.
Thanks a lot to anybody who can share some info on this!!!!
Peace

[centip3de]

Hi all!
As you may already yourself fully be aware of, PDF files sometimes come with annoying security locks that don't let you copy the text. As a student that does a lot of research this feature must be the worst idea ever. I know there are scripts/programs online that will unlock the PDF file for you, but I want to learn to unlock PDFs myself.
Can anybody provide some insight as to what exactly needs to be changed in the PDF file to remove the security locks? Is a disassembler necessary? Once again, I am not looking for links to scripts/programs online that will do it for me.
Thanks a lot to anybody who can share some info on this!!!!
Peace

Unless you have explicit authorization from the PDF author, this is illegal, and as such those on HTS cannot help you.

[limdis]

Unless you have explicit authorization from the PDF author, this is illegal, and as such those on HTS cannot help you.

I think you jumped a little too quickly here. He never mentioned intent to do anything illegal or stated he had any document that did not belong to him. The student history story in and of itself is only a matter of opinion. Additionally, he did mention knowing about programs to crack PDFs, expressing he has the knowledge to do so. He simply asked how the process works.

This request is clear in my book

I know there are scripts/programs online that will unlock the PDF file for you, but I want to learn to unlock PDFs myself. Can anybody provide some insight as to what exactly needs to be changed in the PDF file to remove the security locks? Is a disassembler necessary? Once again, I am not looking for links to scripts/programs online that will do it for me.

[greenburn]

@centip3de: what are u farming post count with useless comments like that? or maybe licking out admin's butt hole sparkly clean?

@limdis: that is exactly what I'm saying - I want to know how the process works.

the security lock is stupid for at least 2 reasons. one - it can be removed, so it only really protects from a portion of the world's population. two - it is preventing students like me to easily write-up bibliography because instead of copy/pasting the titles in the proper format it is necessary to retype them manually.

as far as I can deduce, unlocking a PDF file has something to do with PostScript

[limdis]

@cent: It's been a little bit since we've seen some action, and I know you can handle yourself so I'll let you respond in your own way

@green: No need for hostilities.


Read --wait a sec I linked the wrong one-- to get your started on the HOW it works.

[greenburn]

Thank you for your reply, limdis. I don't think it has something to do with PKI. The file isn't encrypted or completely locked for viewing, it simply disables the ability to copy text. I'm thinking the trick is finding the place in the source code of the PDF file where it sets the flag to disable this ability. The reason I think so is because the online scripts that unlock PDF files do it fast (as fast as it takes for the file to upload), so it doesn't seem like they are bruteforcing a key.

[limdis]

OK I have the PDF downloaded just have I remember where I got it.


EDIT:
In regards to read only, is your file read only password protected or only enabled? It makes a difference

[greenburn]

there is no password. anybody can open the file and view it, etc. you can select the text, but it doesn't let you copy it.

[limdis]

I asked because there are 3 different layers to securing PDFs. Without applying a password read-only is as simple as a T/F variable. First thing you want to check right off the bat is if you can change the settings yourself in properties. Depending on how and with what the document was secured with the option for read-only might be enabled but not password protected to disable it. Sometimes read-only's can be worked around by using the save copy function, or opening the document in Firefox/IE/whatever. If however there is a password prompt to change the setting it is not going to be a quick fix unfortunately.

-- Tue Jan 31, 2012 5:24 pm --

It's not the PDF I have, but explains how older versions encryption process worked. If there is a password on the document anywhere to change settings, consider the entire file encrypted. You can view the text but it can only be viewed through adobe. The entire code is changed, so if you look at the source it will be a mess (link below illustrates my point on how complicated the encryption process is). What anti-adobe security programs do (as you mentioned above), they reverse the encryption process making it legible and spits the password back out at you. Which is why they are so fast. They are specifically designed to reverse engineer PDF documents. Your general cracker will simply bruteforce or dictionary attack, which could take forever depending on how complicated the password is.

http://www.cs.cmu.edu/~dst/Adobe/Galler ... yption.txt

[greenburn]

I checked if it was a read-only file before posting my question in the forum, but it is not read-only. I also know that opening the file in Google Docs lets you bypass the copy restriction. Even so, I want to know how to do it locally.

The Security Method is set to "Password Security" with a Permissions Password

THANKS LIMDIS FOR THE SWEET TUTORIAL!!!!!!!! I think it's just what is needed. Gonna have a read...